Thermal infrared cameras are well known and used in a wide variety of applications. A typical thermal infrared camera, often referred to simply as an infrared camera or IR camera, uses an infrared detector to detect infrared energy that is provided to the infrared detector through an infrared camera lens—a lens capable of transmitting infrared energy. The infrared camera may also include a display for a user to view images generated by the infrared camera based on the infrared energy, or the images may be stored by the infrared camera or transmitted (e.g., via a wireless or wired network) for remote viewing and/or storage.
Infrared detectors for such infrared cameras can be formed using wafer level packaging (WLP) techniques to form microbolometer vacuum package assemblies (VPAs). During WLP operations, a wafer assembly having multiple semiconductor wafer layers is diced to form multiple circuit packages such as infrared detectors. Dicing equipment is commonly aligned with the wafer assembly using alignment marks formed on an outer surface of the wafer assembly.
As electronic devices such as mobile phones and cameras become smaller and thinner in response to consumer demand for compact devices, it is sometimes desirable to reduce the thickness of a circuit package for such devices by thinning one or more of the wafer layers prior to singulation of the individual circuit packages from the wafer. However, it can be challenging, particularly in the case of semiconductor wafers for infrared detectors due to the optical properties of the wafer materials, to align dicing equipment or other processing equipment with a wafer assembly that has been thinned because the thinning can remove the surface on which the alignment marks are typically formed.
Accordingly, a need exists in the art for reduced thickness infrared detectors and WLP methods, systems, and apparatuses that accommodate that enable volume production of such detectors.